Forming of containers

ABSTRACT

A method for forming containers comprises selectively heating a first web and second webs, joining together the first web and the second web along intended outlines of containers so as to form pouches bounded by the intended outlines and conduit means leading out into the pouches, the conduit means being suitable to inject therethrough a forming fluid, forming the containers by expanding the pockets by injecting the forming fluid through the conduit means apparatus for forming containers, comprises indexing a first web and a second web of sheet material through a heating station provided with selective heating means arranged to selectively heat the first web more than the second web and through a welding-and-forming station in which opposing portions of the first web and second web are joined together by welding-and-forming means along intended outlines of containers so as to form pouches and conduit means leading out into said pouches to inject therein a forming fluid and form the containers by expanding the pouches.

CROSS REFERENCE TO RELATED APPLICATIONS

Applicant claims priority under 35 U.S.C. §119 of Italian ApplicationNo. MO99A000288 filed Dec. 31, 1999. Applicant also claims priorityunder 35 U.S.C. § 365 of PCT/EP01/00068 filed Jan. 2, 2001. Theinternational application under PCT article 21(2) was published inEnglish.

BACKGROUND OF THE INVENTION

1. Prior art

WO-94/08852 discloses a forming system in which there are arranged insuccession a preheating station for preheating of sheet material, awelding station, in which opposing regions of the sheet material arejoined along intended outlines of containers so as to define poucheswhich are interconnected by conduits through which a forming fluid canbe injected, a forming station, in which the forming fluid is injectedinto the pouches in order to expand the pouches up to form therefromgroups of containers, the formed containers being joined together byundeformed portions of the sheet material, a cutting station in whicheach group of containers is severed from the sheet material and advancedthrough a filling station, in which product is introduced into theformed containers through openings thereof, a sealing station in whichthe containers are sealed by closing said openings, and a cuttingstation in which the formed and sealed containers are cut out from theundeformed sheet material.

EP-0692364 discloses a similar forming system in which at least onefurther sealing and forming station is interposed between the weldingstation and the forming station, which allows more gradual forming ofcontainers.

Peelable containers which comprise a bulged wall joined together alongits outline with a planar wall, the planar wall comprising a barriersheet peelably detachable from a permeable sheet welded to said outlineare known. Thus, when the barrier sheet is peelably removed from saidpermeable sheet, the container contents can be emanated in the ambientatmosphere through the permeable sheet.

In the peelable containers according to the prior art, removal of thebarrier sheet implies gripping one external portion thereof and tearingaway the barrier sheet from the permeable sheet. However, gripping ofthe barrier sheet is difficult to achieve because the barrier sheet andthe permeable sheet adhere to each other.

SUMMARY OF THE INVENTION

An object of the invention is to improve forming of containers.

Another object of the invention is to improve opening peelability ofcontainers.

According to a first aspect of the invention, a method for formingcontainers is provided. The method comprises heating sheet material,joining together first and second webs of said sheet material alongintended outlines of containers so as to form pouches bounded by saidintended outlines and conduit means leading out into said pouches, saidconduit means being suitable to inject therethrough a forming fluid,forming said containers by expanding said pockets by injecting saidforming fluid through said conduit means, characterized in that, saidheating comprises selectively heating said first web more than thesecond web.

According to a second aspect of the invention, an apparatus for formingcontainers is provided, comprising indexing a first web and a second webof sheet material through a heating station and through awelding-and-forming station in which opposing portions of said first weband second web are joined together by welding-and-forming means alongintended outlines of containers so as to form pouches and conduit meansleading out into said pouches to inject therein a forming fluid and formsaid containers by expanding said pouches, characterized in that saidheating station comprises selective heating means arranged toselectively heat said first web more than said second web.

Owing to these aspects of the invention, it is possible to work withwebs of different materials, without incurring the risk that excessiveheat damages any of the webs.

According to a third aspect of the invention, a method for formingcontainers is provided. The method comprises heating sheet material,joining a first web and a second web of said sheet material alongintended outlines of containers so as to form pouches bounded by saidintended outlines and conduit means leading out into said pouches, saidconduit means being suitable to inject therethrough a forming fluid,forming said containers by expanding said pouches by injecting saidforming fluid through said conduit means, characterized in that, saidexpanding comprises expanding outer regions of said sheet materialexternally of said intended outlines so as to form in each container anopening region in which said first web and said second web are spacedapart from each other.

According to a fourth aspect of the present invention, an apparatus forforming containers is provided, comprising indexing a first web and asecond web of sheet material through a heating station and through awelding-and-forming station in which opposing portions of said first weband second web are joined together by welding-and-forming means alongintended outlines of containers so as to form pouches and conduit meansleading out into said pouches to inject therein a forming fluid and formsaid containers by expanding said pouches, characterized in that saidwelding-and-forming means is provided with recess means for receivingregions of said sheet material externally of said intended outlines, insaid regions said first web being distanced apart from said second webso as to define facilitating activating means of said container.

According to a fifth aspect of the invention, a container is provided.The container comprises first wall means and second wall means definingan interior cavity in which a product is contained, a peripheral weld atwhich said first wall means and said second wall means are joinedtogether, said second wall means comprising a peelable sheet peelablydetachable from a permeable membrane welded to said first wall means atsaid peripheral weld, characterized in that, said first wall means andsaid second wall means are distanced apart from each other at an outerregion externally of said peripheral weld to define a gripping zone ofsaid second wall means.

In this way, containers having a facilitating peelability zone areformed in a particularly simple and economic way.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood and carried out with reference tothe drawings attached which show exemplifying and not restrictiveversions thereof, wherein:

FIG. 1 is a front schematic view of a machine for forming containersfrom sheet material;

FIG. 2 is a section taken along the plane II-II of FIG. 1;

FIG. 3 is a highly enlarged and broken section of a version of theinjection nozzles of the forming fluid;

FIG. 4 is a section as FIG. 2, but relative only to the sealing andforming station with mould in a closing position;

FIG. 5 is a front view of a peelable container;

FIG. 6 is highly enlarged and broken section along the plane VI-VI ofFIG. 5;

FIG. 7 is a section as FIG. 6, but relative to a partially opencontainer, i.e. an activated container;

FIG. 8 is a front view of a mould part for peelable containers;

FIG. 9 is a view as FIG. 8, but relative to a variant of the injectionmeans of the forming fluid;

FIG. 10 is a highly enlarged and broken section taken along the planeX-X of FIG. 8 relative to a complete mould.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1, 2 and 3, a machine for forming containers comprisesin sequence: a heating station 2 wherein a first web 8 of thermoformablesheet material and a second web 10 of sheet material (not necessarilythermoformable) are heated, a welding-and-forming station 4, in whichthe first web 8 and the second web 10 are welded along intended outlines12 of precursor containers, or pouches, 12 a and a forming fluid isinjected through injectors 14 in order to form containers defined by thecontours 12 and a stabilizing station 6 wherein the shape of the formedcontainers 16 is stabilized. Downstream of the stabilizing station 6,advancing means 18 is provided in order to advance by steps the firstsheet 8 and the second sheet 10 from the stations 2, 4 and 6 toward acutting station 20 wherein groups 22 of formed containers 16 areseparated from the sheets 8, 10 by cutting means 21.

The heating station 2 includes a heating unit 24, such as a heating lampunit, facing the first web 8 and a screen 25 disposed between the firstweb 8 and the second web 10. In this way, the first web 8 is heated morethan the second web 10. For example, if the first web is constituted byplastic material, it will attain a temperature very close to thesoftening temperature (nearly about some hundred centigrade degrees).The second sheet 10 is only slightly heated, for instance nearly aboutto a temperature of some ten centigrade degrees.

In the sealing-and-forming station 4, a first mould portion 26 isprovided having hollows 28 suitable to receive corresponding regions ofthe first sheet 8 when forming fluid is injected through the injectors14. The injectors 14 extend internally into the screen 25 so as toproject from it toward the sealing and forming station 4 and laterallyso as to be connected with ducts of pressurized air, not shown.

In a version not shown, the injectors can also be inserted laterallybetween the first mould portion 26 and a second mould portion 30cooperating with the first mould portion 26 in the position shown byarrow F1.

The first mould portion 26 is cooled, so that, when the material of thefirst web 8, which is deformed by the action of the forming fluid, comesinto contact with the cold walls of the first portion 26 of the mould,it cools, assuming thereby its final shape and dimensions.

The second mould portion 30 is substantially planar, i.e. without thehollow opposed to the first portion 26 of mould, so that, when the firstmould portion 26 and the second mould portion 28 are moved in a closingposition, they lock corresponding portions of the first web 8 and of thesecond web 10 between them.

The second mould portion 30 is heated, so that the second sheet 10,which lies at a relatively low temperature, is heated up to atemperature suitable to allow to seal it to the first web 8 along theintended outlines 12.

The stabilizing station 6 includes a further first mould portion 32 anda further second mould portion 34, structurally analogous to the firstmould portion 26 and to the second mould portion 30, respectively.

However, one or both of the further first mould portion 32 and thefurther second mould portion 34 can be cooled.

The further second mould portion 34 is not heated, because this mightdamage the effectiveness of the weld along the intended contours 12which is carried out at the welding-and-forming station 4.

The further second mould portion 32 is provided with further hollows 36slightly greater than the hollows 28 of the first mould portion 28 tostabilize the final shape and dimension of the formed containers.

As seen in FIG. 8, a mould 40 of a version of the welding-and-formingstation 4 has depressions 42 for receiving the material of the first web8 deformed by the forming fluid and shows also grooves 44interconnecting the depressions 42, forming canalizations for theforming fluid defined by the first web 8 and the second web 10.Furthermore the grooves 44 can extend up to define further grooves 46suitable to form in the first web 8 marginal regions 52′ of externaledge of container distanced apart from corresponding regions of thesecond web 10.

In this way, it is possible to manufacture a container 50 as shown inthe FIG. 5, wherein a marginal region 52 of a peripheral weld 54 of acontainer 50 containing a liquid 51 shows a first edge zone 56 of thefirst web 8 formed so as to lie substantially detached from thecorresponding second edge zone 58 of the second web 10. In this way,when a peelable container has to be activated, in order to cause apermeable film 58 to transpire, so as it can emanate volatile substancesin the surrounding environment, it is sufficient to grip one of theedges 56, 58 at the marginal region 52 and to remove a barrier layer 60initially associated to the permeable film 58.

Advantageously, the second edge zone 58 of the second sheet 10 can alsobe fully formed so as to increase distance from the first edge zone 56of the first sheet 8.

As shown in FIG. 9, the further grooves 46 can be fed with pressurizedforming fluid independently, i.e. through inlet 62.

As shown in FIG. 10, in order to make forming of the edge 56 of thefirst sheet 8 easier, it is possible to obtain an additional recess 64in the further grooves 46 at a region designed to form a portion of theedge 56 closer to the weld 54.

1-30. (canceled)
 31. A container, including first wall means (8) andsecond wall means (10) defining an interior cavity in which a product(51) is contained, a peripheral weld (54) at which said first wall means(8) and said second wall means (10) are joined together, said secondwall means (10) comprising a peelable sheet (60) peelably detachablefrom a permeable membrane (58) welded to said first wall means (8) atsaid peripheral weld (54), characterized in that, said first wall means(8) and said second wall means (10) are distanced apart from each otherat an outer region externally of said peripheral weld (54) to define agripping zone of said second wall means (10).